What does setscrew mean?
A setscrew is a specialized fastener used to hold a machine part in a fixed position. Unlike an ordinary screw, which normally joins two pieces through matching threads, a setscrew bears against a surface or component and is tightened to prevent movement, loosening, or unwanted rotation. Setscrews are used on shafts, collars, pulleys, and similar mechanisms, often where one part must be locked rather than two lengths of material joined. The term is especially associated with engineering and workshop language, although it remains ordinary vocabulary for anyone maintaining machinery. The expression describes what the fastener does: it “sets” a component in position. It should not be confused with a general screw, since its purpose and often its specialized form are different. Both “setscrew” and “set screw” are standard English forms, with usage varying by technical tradition and source.
nounA small screw or screw-like fastener that is tightened against a component to secure it, prevent it from moving, or hold it in a fixed position.
- A small screw or screw-like fastener tightened against a component to lock or secure it in a fixed position.
"He tightened the setscrew to lock the collar securely onto the shaft."
"Loosen the setscrew before sliding the collar onto the shaft."
"The setscrew prevents the pulley from rotating independently of the drive shaft."
The regular plural is used when referring to several setscrews, especially when tightening or replacing them.
"The mechanic replaced all four setscrews before testing the assembly."
Its name is a job description: a setscrew “sets” a part in position.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does setscrew come from?
Setscrew is an English compound formed from set and screw. In its mechanical sense, set means to place, fix, or adjust something in position, while screw refers to the threaded fastener that applies pressure or holds a component in place. The compound name therefore describes the fastener's function of setting or securing a part.
How setscrew is actually used
This is chiefly technical and mechanical vocabulary. Both “setscrew” and the open compound “set screw” are standard spellings, with usage varying by technical tradition and source.
Easily confused with setscrew
A screw is a general threaded fastener, whereas a setscrew is specifically tightened to hold or lock another component in position.